Right out of the gate, make sure the kegs are really, really clean. Take the keg apart, including all of the posts, dip tubes, lines, o-rings, etc., and soak those in PBW (or similar cleaner) for a few minutes. Then put it back together and fill the keg itself with cleaning solution. Let it sit for 30 minutes, then flush it with CO2 to get the lines clean as well. Repeat if you see any remaining gunk or smell something off.
When you're ready to keg, you'll want to sanitize the keg first. Fill the keg with sanitizer (StarSan or Iodaphor), let sit for a few minutes. While you're doing this, you can spritz some sanitizer into the gas line to santize that as well. Then flush with CO2 to get the beer line sanitized. Then, you're ready to keg.
If you are kegging without cooling the beer down, consult various beer carbonation charts (e.g.,
http://www.kegerators.com/articles/carbonation-table-pressure-chart.php) to get the pressure right. Carbing is a function of time, pressure, and temperature of the beer. If your beer is relatively warm, you need to up the pressure, otherwise you won't get the right carbonation level.
When it comes to serving, good luck doing that with room temp beer. You'll likely have a lot of foaming problems. So at a minimum, try to clear some space in a refrigerator to cool it down before serving. Cooling the beer down before/during carbonation would be even better.
I'm still working on my keezer, so for the time being I've been using the chest freezer without modification (other than a Johnson controller) and using picnic taps to dispense. Works great while the more permanent set up is in the works.
